Carburetor



Nov. 6, 1928.

H. w. ALLEN CARBURETOR Filed Jan. 25, 1922 2 Sheets-Sheet 2 A TTURNEYS Patented Nov. 6,1928.,y

UNITED STATES HERBERT WILLIAM ALLEN, or EEEsrio, caniroENrA. f

CARB UR-ETOR.

Application ledranuary 254 1922; Serial No. 531,799.

This invention relates to carburetors espeeially adapted for application to the power units of motor vehicles and flying machines of various types.

Briefly stated an important object of this invention is to provide avcarburetor having novel means for' supplying a; mixture of air and fuelin suoli relative proportions'as to producethe best results in the engine undery the specific conditions of load and altitude under which itj maybe operating atany given time and to supply this mixture in a thorf` oughly gasified conditionand at a temperatui-eras low assis Censis-ent with the fuel being used. l i

Further an important aim of theinvention is to provide a ycarburetor wherein the fuel level may be maintained substantially ,below the discharge end of the spray nozzle vfor eliminating theirregular action oi the carburetor when the engine is abruptly tilted or inclinedas the result of the travel of the vehicle over rough 'roads` l f Y The invention forming the'subject matter of this application is also provided with lmeans for utilizing fuels of different grades, the lowergrade fuel being thoroughly heated and gasified prior to its final mixture with a properlproportion of' air. Other objectsand advantages ofthe invention will be apparent during the course of the following description. r

In the accompanying drawings -forming a part of this application and in which like numorals are employed to designate like parts throughout the same, n i

Figui-e1 is a perspective of the improved` carburetor.y

Figure'Q is a group control mechanism em tion. Figure 3 is a detail sectional view through a nozzle and associated elements.y n y Figure l 'is a vertical. sectional view through the improved carburetor` l Figure 5 is a horizontal sectional VView through the carburetor, the view being taken on line 4--4 of Figure 4.V

In the drawings wherein fort-he purpose of illustration is shown a preferred embodiment of the invention the numeral ldesignates a casing having its upperportion provided with a nipple 11 provided with radially arranged lugs 12 upon which the flared lower end 13 of a tubularmeinberl is mounted.

perspective of a fuel odied inthe inven- Figures tand 4` clearly illustrate that screws 16. are extended through the flared portion 13 of the tubular member 15 and are engaged with the radially arranged lugs 1Q y for the pur iosc of securely connecting the enlarged. portion 13 to the casing# It will be seen thatsince the radially arrangedv lugs 12 are arrangedin spaced relation, a substantial air inlet space is providcdfor permitting a sulicient quantity of air to enter the eniarged tubular portion 15. The upper end ofthe tubular portion 15 is provided with a coupling member'18 having a-flange 19 connected to the attaching flange 2O ofthe intake manifoldV y21 by means of -cap screws 23 or the like. A butterfly valveQ' Ais arranged in the coupling member 18l andis provided with an arm 26 having connection with a control rod Qrwhich extendsto a suitable point of control. lhe buttery valve 25 is the throttle valve.` f

The high grade fuel or thepriming iluid is fed into a fuel pipe 29 having avalve 3() con nected to-the upper portion of the casing 10 and having communication with a passage 31, which in turn communicatesv withan an'- nular passage 3 2 in the nipple 11. e

As illustrated infFigure'la choke tube 34 is threaded into the nipple 11 andis pro vided with anfannular flange B5-havin its upper side recessed or dished to provi e .a

valve seat tor the lower end of va sleeve valve 37. The annular'flangef is also provided with a series of openings 38 which communicate with the annular passage 32. i v Vhen the'engine is at rest the valve 37 is down against its seat, and in the preferred embodiment of this invention the high grade fuel may be maintained ata level below the' *Y top of the openings 38 any suitable means. When the engine is startedthe partial vacu um producedby lthe engine'pistons causes' .thef'valve 37 to rise from its seat, and the reducedpre'ssure vat the same time, causes high grade fuel to issue through the openings 38 where it is picked up by the air entering between lthe sleeve valve 37 and the flange 35, vand is carried into the engine cylinders through the tubular member 15 and engine manifold l21.

The sleeve valve 37 which isl controlled by the vacuum caused by the operation of f the engine pistons is provided withan 4annular rib l0 which operates between an an-V nular shoulder ll in the. tubular member .15 and thelower end of the coupling mem@ ber 1S.-` The spf-ieebetween the ular rib` 40 and the annular shoulder 4i supplied with air by means f aseries of openings 43 in the shoulder 4l. By thus supplying a quantity of air to the space between the rib 40 and the annular' shoulder 4l the valve 37 may move upwards without creating a Vvacuum in the said space, and likewise the wvill come in contact. with the tube 47 and thereby7 volatilize the fuel in the saine,

The passage 46 has a butterfly valve 49V interposed in it. This butterfly valve has an arm 5l connected to a link which is connected to the arm 53 of the valve 36, as illustrated in Figure l, so that *he fuel control valve 30 and the butterfl valve 49 are operatively connected, the gci'neut being such that when the valve 30 is opened for admitting fuel through the pipe 29, the butterfly valve 49 will be'closet ,thereby closi g t passage 46. n the other hand when the valve 49 is opened the partial vacuum in the casing l will cause fuel to be sprayed into the gasiiying tube 47 and to be drawn through it andthrough the passage 46, while, at the same time the valve will be closed, thus cut ing off the fuel supply from 29. rlhe elements described in this paragraph there- Vfore constitute means whereby fuel may be drawn from either of the two sources noted.

As illustrated in Figures 3 and 4 a-nozzlc 55 is adapted to supply liquid fuel. to the U-shuped heating tube 47 from a chamber 8 in the lower portion of the casing 1 0. The axis of the spray nozzle in alignment with that branch of the tube 47 connected with the nipple 56 and a choke member 56 is fitted into the nipple 56. This ehokeinen'iber 53 is so formed as to produce a decided constriction of the air passage between the choke member 56 and the outside of the nozzle at afpoint just below the top of Vthe nozzle .55.V This constriction is for the purpose of producing` and is so adjusted in dimensions as to produce7 a lowering of pressure at the upper end of the nozzle so that the atmospheric pressure act.- ing on the surface of theliquid in the chamber 60 is transmitted through the liquid fuel to the end of the nozzle amL causes the liquid fuel to issue from the nozzle where it mixes with the air entering through a plurality of openings 6l and passes on to the tube 47.

The second constriction produced by the choke member 58 and the metering pin or needle valve 63 is for the purpose of producing a still` higher velocity of the air and liquidfuel in order to more complet-ely break up the liquid fuel into a fine spray. Another definite function of the second constriction formed by the metering pin and the 4choke member and to a lesser extent the first constriction is to liiiit the amount of air admitted at this point to the least possible amount consistent with the production of a lfine spray. lt is not intended to provide air at this point primarily for evaporating the liquid fuel but as a means for spraying the liquid into the heating tube.

By thus limiting the amount of air admitted to the heating tube specific and marked advantages are obtained as will be hereinafter set forth. Y

The liquid fuel is supplied to the nozzle 55 from the chamber 8 which in turn is supplied with fuel from the float chamber 60 having a float 66 connected to a needle valve 67 by means of a lever 68 pivoted intermediateits ends to a pin 69. When the level of the liquid in the chamber 60 rises theV float is elevated and the pin 67 is seated thus cutting off the supply of fuel from the fuel supply pipe 70. In practice the fuel in the chamber 60 is maintained at a level above the chamber 8 and below the top of the nozzle 55.

The metering pin or needle valve 63 is slidable in a bushing 7 2 threaded into a nipple 73 in thelower portion of the easing 10. A`

plug 74 is threaded into the lower end of the bushingr72l andinay be removed when it is desired to engage a screw driver with the slotted lower end of the metering pin 63 for the purpose of adjusting the saine. The proper opening in the spray `nozzle for an idling condition is-secured by adjusting the height of the metering pin 63. This adjustmentis secured by turning the metering pin 63 in a'nu't 7 5 threaded onthe intermediate portion of the pin. The nut 75 has laterally projecting pins S0 which are received in longitudinal slots formed in the forked arm of the lever 76 which is pivoted intermediate its ends as indicated at 7 7. A coiled spring 82V is confined between the face of nut 7 5 and bushing 72 and forms a means for urging the metering pin 63 upward, whereby the lost motion between the metering pin and the valve 37 is taken up. v

With particular reference to Figure 2 it will be observed that the valve 37 is provided with a spider35 to which vc-iiicalli7 movable rod 86 is connected. The. lower end of the rod86 is provided with a laterally projecting arm 87 arranged beneath the adj acent portion of the lever 76 and having engagement with the roller 90 carried by one of the laterally directed terminal portions of a link 9.1. The roller 9() operates between the opposed sides of the arm V87 and the lever 76 and may be adjusted longitudinally of the same members.

When the roller 90 isset close to the pivot pin 77 the movement ofthe lever 76 will bel in-l creased when the valve 37 is elevated'. On the other ,hand when the roller 90' is set close to the rod 86, the movement of the lever will be lessened, thus correspondinglydecreasingthe movement of the metering pin 63 for a `given movement of valveN 37.

The link l91 is providedl with a laterally directed terminal portion having connection with an adjusting screw 93 slidable through a stalling' box 94 at one end of the chamber 8 and having connection with an adjusting nut screw 93 so that the position ofthe roller 99 may be varied at the will of the operator.

It is evident that when a more viscous fuel is being used a greater lowering of the metering pin will be required than when a less viscous fuel is beingused. The above described arrangement is provided to make the carburetor adaptable to different fuels having different vscosities. v

The vertically movable rod 86 is slidable through a bearing 98 extended up through the passage 46 and cooperating with vthe choke member 34 in reducing' the fuel passage in cross sectional area.- By depending principally onheat to duce vaporization'of the fuel in the tubel a much quicker response is obtained. Some carburetors are slow to respond to increased demands on the engine especially when using lower grade fuels such as kerosene7 but that. after a few seconds at the most, the motor respends in a satisfactory manner. Y

In ractice it has been found that by spraying t e fuel into the interior of a hot tube and depending mainly on the heat to produce the vaporization of the fuel as is ythe case in this invention, an instantaneous response is obtained to increased demands so that an automobile equipped with this carburetor accelerates as readily when using kerosene as when using a higher grade fuelsuch as gasoline.

In some other carburetorszwhen the total air or a considerable portion of it passes through the vaporizing tube it has been found difficult to obtain a tube of suchy dimensions as to give a satisfactory result at all lfoads especially when using the lower grade nels. heated when the motor is running on light load tendsto become `excessively heated on heavy loads. By cutting down the quantity of air admitted to the gasifying tube to a minimum as herein set forth and at the same time reducing the size of the gasifying tube and leading all the products of combustion past the outside of said tube, the increased" amount of heat extracted from a gaslfying pron e A tube which can be satisfactorily tube the greater amount of fuel is balanced at hea-vier loadsy by the greater amount of heat given ofi by the exhaust gases to the gasifyingtube so that perfect vaporization with i out excessive heating of the ygasifying tube is obtained at all loads. A

I ain aware that the utilization turi principle in' connection with thespray of the Vennozzle in the carburetor is in a broad sense not` novel. 'Specific vimprovement is claimed in theuse of a very restricted opening so lo- L f. e.

cated that the atomizing air nrst passes this restricted opening before it comes in contact with the liquid fuel or before it reaches the point at which the liquid fuel issues from the spray nozzle. In this manner the velocity' of the airis greatly incrcased-at'gthe vpoint at which'it contacts 'with the liquidfuel. By the use of such a very restricted opening in connection with the pressure regulatingy valve -37 the velocity of the air is maintained prac- 'It has been found` desirable to vemploy the second constriction between the metering pin and the chokemember 58 as the employment of only one constriction would makenecessary the use 4of an extremely small opening in the spray. nozzle. Such an opening is hard to regulate and is liable to clog with foreign matter. Also by employing the sec'- ond constriction as illustrated in the drawingthe use ofa larger opening in spray noz zle is possible. The second constriction located between the metering pin 63 and choke member 58 serves the additional purpose of producing a finer spray with the saine quantity of air than is Ypossible by using a single constriction. As is wellknown, some carburetors, when adjusted to give a suitable mixture of air and fuel when operating at lower altitudes, give a mixture which is too rich in fuel when operating at higher altitudes. This tendency of the mixture to become too'v rich at higheraltitudes is automatically conixpensated for inthe present carburetor by maintaining the proper proportions between thespray nozzle, the several constrictions, the size of the gasifyi-ng tube and the passage 46 and more particularly by providing the proper sized opening inthe choke member When fuel is volatilized in an arrangement as shown7 it isevident that a given volume of the liquid fuel when vaporized at higher altitudes will expand yto greater volume than the same amount of liquid vaporized at'lower altitudes dueto its being subjected to less pressure aty higher altitudes. Therefore at higher altitudes greater difference in pressure betweenV the inthe pasf sage 46 and the mixture in the tubular inem-Y i Y being identical greater back pressure Will be produced by the vaporized fuel in the chainber 46 at higher a titudes and since'as hereinbefore set forth the valve 37 maintains a practically constant difference of pressure between the mixture in the easingand the ouh side air it evident that the greater back pressure produced in the casing f6 and gasifyi'ng tube at higher altitudes acts to decrease the eiiectire pressure difference causing the fuel to feed tl'irough the spray nozzle and consequently less fuel is fed from the nozzle to the gasifying` tube. Thislesser amount of fuel compensates for the lesser Weight of air passing into carburetor and engine at higher altitudes, and a desirable ratio of fuel and air is maintained.

* lhile the pressure r shown as aI sleeve valve, it s obvious that any suitable form of valve may be employed.

Itis Well known that most carburetors lat-ingl valve 37 when adjusted to give a suitable mixture in cold Weather give a mixture Which is too rich in Warm Weather or on hot days. This difieulty is partially compensated for in this carburetor through the medium of the same elements that compensate for the changes in air pressure caused by changes in altitude. Itis evident that other conditions being identical when the outside air is Warnr er the carburetor and its gasifying tube is Warmer than on cold days and thatin general the carburetor and the liquid fuel con- -tained therein is Warmer When the gasifying,`

tube is Warmer. The higher the temperature to which the fuel is eated inthe gasifying tube the greater its volume and the greater the consequent baelrpressure generated .in the gasifying tube. This greater bach pressure tends to decrease the effective pressure feeding` the liquid fuel into the gasifying tube and this decrease in effective feeding,l pressure tends to decrease the iloiviof fuel and partially compensates for the tendency to greater flow caused by decrease in viscosity of the liquid fuel at higher temperatures and a desirable ratio of fuel to air is maintained.

Having thus described my invention What l claim is A carburetor comprising a liquid fuel spray nozzle, a heating tube having' anV enpanded end in communication with the spray nozzle, a choke tube having' one end in cornmunioation With the remaining end of the heating; tube and its other end in communication with the outlet ofthe carburetor7 said heating` tube having the opposite end thereof expanded for a portion `of its length7 said heating tube being U-shaped and of restricted diameter throughout the .greater portion of its length and bet-Ween rthe expanded ends hereof.

, HERBERT WILLIAM Annan. 

